Good day all , I picked up a 71 Lightning Engine prefix GE that had a knock in the engine.I ran and thought it was a gudgeon noise Ended up being a bent rod which i swapped over.The puzzling thing is
that it had only outer valve springs?? it ran ok apart from the knock.Further investigation...the head and engine has been recond not that long ago( kms). the serial number on the head is 68-466 z AM Z2.
The head is a 28mm port head match ported to the 30 mm amals (new) . it has a finned rocker cover but no head brace.The valve springs are 44.45mm free length. and 5 coil I think
My question is what valve springs would suit this head?
Thanks in advance Pete
You have an assortment of components there!! The engine would have been built approximately June 1971, but the Cylinder Head as far as I can tell is from a 1964 model year bike. BSA part numbers for cylinder heads were 68-0465, A65 Lightning Rocket or 68-0467, A50 Cyclone. The valve springs would originally been available with different part numbers for inner and outer from BSA, but if you use 68-0475 as the spring part number it'll list a set of 4 inner and 4 outer ones.. HTH.
Hi,
Re suitable valve springs. All that seems to be available these days are generic springs to fit all years and it looks like all suppliers stock and sell the same make of springs.
Dave.
Thanks for your help
Pete
Later springs will be fine in earlier head. I am using a 68-466 (which is the casting number head) on one of my bikes, I'm using the SRM race springs in this application. Any of these springs branded Hepolite are junk, the ones sold by SRM now are the same junk. They used to be very good. Till they swapped suppliers.
If you want some top quality springs which will fit perfectly, are suitable upto about 8000 rpm but not too hard on the cam, E&V engineering in Michigan sell them. Not cheap but very good.